<?php
/**
 * Zend Framework
 *
 * LICENSE
 *
 * This source file is subject to the new BSD license that is bundled
 * with this package in the file LICENSE.txt.
 * It is also available through the world-wide-web at this URL:
 * http://framework.zend.com/license/new-bsd
 * If you did not receive a copy of the license and are unable to
 * obtain it through the world-wide-web, please send an email
 * to license@zend.com so we can send you a copy immediately.
 *
 * @category   Zend
 * @package    Zend_Service_Amazon
 * @subpackage Ec2
 * @copyright  Copyright (c) 2005-2009 Zend Technologies USA Inc. (http://www.zend.com)
 * @license    http://framework.zend.com/license/new-bsd     New BSD License
 * @version    $Id: CloudWatch.php 19067 2009-11-19 22:13:54Z sidhighwind $
 */

require_once 'Zend/Service/Amazon/Ec2/Abstract.php';

/**
 * An Amazon EC2 interface that allows yout to run, terminate, reboot and describe Amazon
 * Ec2 Instances.
 *
 * @category   Zend
 * @package    Zend_Service_Amazon
 * @subpackage Ec2
 * @copyright  Copyright (c) 2005-2009 Zend Technologies USA Inc. (http://www.zend.com)
 * @license    http://framework.zend.com/license/new-bsd     New BSD License
 */
class Zend_Service_Amazon_Ec2_CloudWatch extends Zend_Service_Amazon_Ec2_Abstract
{
	/**
	 * The HTTP query server
	 */
	protected $_ec2Endpoint = 'monitoring.amazonaws.com';

	/**
	 * The API version to use
	 */
	protected $_ec2ApiVersion = '2009-05-15';

	/**
	 * XML Namespace for the CloudWatch Stuff
	 */
	protected $_xmlNamespace = 'http://monitoring.amazonaws.com/doc/2009-05-15/';

	/**
	 * The following metrics are available from each EC2 instance.
	 *
	 * CPUUtilization: The percentage of allocated EC2 compute units that are
	 *  currently in use on the instance. This metric identifies the processing
	 *  power required to run an application upon a selected instance.
	 *
	 * NetworkIn: The number of bytes received on all network interfaces by
	 *  the instance. This metric identifies the volume of incoming network
	 *  traffic to an application on a single instance.
	 *
	 * NetworkOut: The number of bytes sent out on all network interfaces
	 *  by the instance. This metric identifies the volume of outgoing network
	 *  traffic to an application on a single instance.
	 *
	 * DiskWriteOps: Completed write operations to all hard disks available to
	 *  the instance. This metric identifies the rate at which an application
	 *  writes to a hard disk. This can be used to determine the speed in which
	 *  an application saves data to a hard disk.
	 *
	 * DiskReadBytes: Bytes read from all disks available to the instance. This
	 *  metric is used to determine the volume of the data the application reads
	 *  from the hard disk of the instance. This can be used to determine the
	 *  speed of the application for the customer.
	 *
	 * DiskReadOps: Completed read operations from all disks available to the
	 *  instances. This metric identifies the rate at which an application reads
	 *  a disk. This can be used to determine the speed in which an application
	 *  reads data from a hard disk.
	 *
	 * DiskWriteBytes: Bytes written to all disks available to the instance. This
	 *  metric is used to determine the volume of the data the application writes
	 *  onto the hard disk of the instance. This can be used to determine the speed
	 *  of the application for the customer.
	 *
	 * Latency: Time taken between a request and the corresponding response as seen
	 *  by the load balancer.
	 *
	 * RequestCount: The number of requests processed by the LoadBalancer.
	 *
	 * HealthyHostCount: The number of healthy instances. Both Load Balancing dimensions,
	 *  LoadBalancerName and AvailabilityZone, should be specified when retreiving
	 *  HealthyHostCount.
	 *
	 * UnHealthyHostCount: The number of unhealthy instances. Both Load Balancing dimensions,
	 *  LoadBalancerName and AvailabilityZone, should be specified when retreiving
	 *  UnHealthyHostCount.
	 *
	 * Amazon CloudWatch data for a new EC2 instance becomes available typically
	 * within one minute of the end of the first aggregation period for the new
	 * instance. You can use the currently available dimensions for EC2 instances
	 * along with these metrics in order to refine the slice of data you want returned,
	 * such as metric CPUUtilization and dimension ImageId to get all CPUUtilization
	 * data for instances using the specified AMI.
	 *
	 * @var array
	 */
	protected $_validMetrics = array('CPUUtilization', 'NetworkIn', 'NetworkOut',
                                    'DiskWriteOps', 'DiskReadBytes', 'DiskReadOps',
                                    'DiskWriteBytes', 'Latency', 'RequestCount',
                                    'HealthyHostCount', 'UnHealthyHostCount');

	/**
	 * Amazon CloudWatch not only aggregates the raw data coming in, it also computes
	 * several statistics on the data. The following table lists the statistics that you can request:
	 *
	 * Minimum: The lowest value observed during the specified period. This can be used to
	 *  determine low volumes of activity for your application.
	 *
	 * Maximum: The highest value observed during the specified period. You can use this to
	 *  determine high volumes of activity for your application.
	 *
	 * Sum: The sum of all values received (if appropriate, for example a rate would not be
	 *  summed, but a number of items would be). This statistic is useful for determining
	 *  the total volume of a metric.
	 *
	 * Average: The Average of all values received during the specified period. By comparing
	 *  this statistic with the minimum and maximum statistics, you can determine the full
	 *  scope of a metric and how close the average use is to the minimum and the maximum.
	 *  This will allow you to increase or decrease your resources as needed.
	 *
	 * Samples: The count (number) of measures used. This statistic is always returned to
	 *  show the user the size of the dataset collected. This will allow the user to properly
	 *  weight the data.
	 *
	 * Statistics are computed within a period you specify, such as all CPUUtilization within a
	 * five minute period. At a minimum, all data is aggregated into one minute intervals. This
	 * is the minimum resolution of the data. It is this data that can be aggregated into larger
	 * periods of time that you request.
	 *
	 * Aggregate data is generally available from the service within one minute from the end of the
	 * aggregation period. Delays in data propagation might cause late or partially late data in
	 * some cases. If your data is delayed, you should check the service’s Health Dashboard for
	 * any current operational issues with either Amazon CloudWatch or the services collecting
	 * the data, such as EC2 or Elastic Load Balancing.
	 *
	 * @var array
	 */
	protected $_validStatistics = array('Average', 'Maximum', 'Minimum', 'Samples', 'Sum');

	/**
	 * Valid Dimention Keys for getMetricStatistics
	 *
	 * ImageId: This dimension filters the data you request for all instances running
	 *  this EC2 Amazon Machine Image (AMI).
	 *
	 * AvailabilityZone: This dimension filters the data you request for all instances
	 *  running in that EC2 Availability Zone.
	 *
	 * AutoScalingGroupName: This dimension filters the data you request for all instances
	 *  in a specified capacity group. An AutoScalingGroup is a collection of instances
	 *  defined by customers of the Auto Scaling service. This dimension is only available
	 *  for EC2 metrics when the instances are in such an AutoScalingGroup.
	 *
	 * InstanceId: This dimension filters the data you request for only the identified
	 *  instance. This allows a user to pinpoint an exact instance from which to monitor data.
	 *
	 * InstanceType: This dimension filters the data you request for all instances running
	 *  with this specified instance type. This allows a user to catagorize his data by the
	 *  type of instance running. For example, a user might compare data from an m1.small instance
	 *  and an m1.large instance to determine which has the better business value for his application.
	 *
	 * LoadBalancerName: This dimension filters the data you request for the specified LoadBalancer
	 *  name. A LoadBalancer is represented by a DNS name and provides the single destination to
	 *  which all requests intended for your application should be directed. This metric allows
	 *  you to examine data from all instances connected to a single LoadBalancer.
	 *
	 * @var array
	 */
	protected $_validDimensionsKeys = array('ImageId', 'AvailabilityZone', 'AutoScalingGroupName',
                                            'InstanceId', 'InstanceType', 'LoadBalancerName');

	/**
	 * Returns data for one or more statistics of given a metric
	 *
	 * Note:
	 * The maximum number of datapoints that the Amazon CloudWatch service will
	 * return in a single GetMetricStatistics request is 1,440. If a request is
	 * made that would generate more datapoints than this amount, Amazon CloudWatch
	 * will return an error. You can alter your request by narrowing the time range
	 * (StartTime, EndTime) or increasing the Period in your single request. You may
	 * also get all of the data at the granularity you originally asked for by making
	 * multiple requests with adjacent time ranges.
	 *
	 * @param array $options            The options you want to get statistics for:
	 *                                  ** Required **
	 *                                  MeasureName: The measure name that corresponds to
	 *                                      the measure for the gathered metric. Valid EC2 Values are
	 *                                      CPUUtilization, NetworkIn, NetworkOut, DiskWriteOps
	 *                                      DiskReadBytes, DiskReadOps, DiskWriteBytes. Valid Elastic
	 *                                      Load Balancing Metrics are Latency, RequestCount, HealthyHostCount
	 *                                      UnHealthyHostCount
	 *                                  Statistics: The statistics to be returned for the given metric. Valid
	 *                                      values are Average, Maximum, Minimum, Samples, Sum.  You can specify
	 *                                      this as a string or as an array of values.  If you don't specify one
	 *                                      it will default to Average instead of failing out.  If you specify an incorrect
	 *                                      option it will just skip it.
	 *                                  ** Optional **
	 *                                  Dimensions: Amazon CloudWatch allows you to specify one Dimension to further filter
	 *                                      metric data on. If you don't specify a dimension, the service returns the aggregate
	 *                                      of all the measures with the given measure name and time range.
	 *                                  Unit: The standard unit of Measurement for a given Measure. Valid Values: Seconds,
	 *                                      Percent, Bytes, Bits, Count, Bytes/Second, Bits/Second, Count/Second, and None
	 *                                      Constraints: When using count/second as the unit, you should use Sum as the statistic
	 *                                      instead of Average. Otherwise, the sample returns as equal to the number of requests
	 *                                      instead of the number of 60-second intervals. This will cause the Average to
	 *                                      always equals one when the unit is count/second.
	 *                                  StartTime: The timestamp of the first datapoint to return, inclusive. For example,
	 *                                      2008-02-26T19:00:00+00:00. We round your value down to the nearest minute.
	 *                                      You can set your start time for more than two weeks in the past. However,
	 *                                      you will only get data for the past two weeks. (in ISO 8601 format)
	 *                                      Constraints: Must be before EndTime
	 *                                  EndTime: The timestamp to use for determining the last datapoint to return. This is
	 *                                      the last datapoint to fetch, exclusive. For example, 2008-02-26T20:00:00+00:00.
	 *                                      (in ISO 8601 format)
	 */
	public function getMetricStatistics(array $options)
	{
		$_usedStatistics = array();

		$params = array();
		$params['Action'] = 'GetMetricStatistics';

		if (!isset($options['Period'])) {
			$options['Period'] = 60;
		}
		if (!isset($options['Namespace'])) {
			$options['Namespace'] = 'AWS/EC2';
		}

		if (!isset($options['MeasureName']) || !in_array($options['MeasureName'], $this->_validMetrics, true)) {
			throw new Zend_Service_Amazon_Ec2_Exception('Invalid Metric Type: ' . $options['MeasureName']);
		}

		if(!isset($options['Statistics'])) {
			$options['Statistics'][] = 'Average';
		} elseif(!is_array($options['Statistics'])) {
			$options['Statistics'][] = $options['Statistics'];
		}

		foreach($options['Statistics'] as $k=>$s) {
			if(!in_array($s, $this->_validStatistics, true)) continue;
			$options['Statistics.member.' . ($k+1)] = $s;
			$_usedStatistics[] = $s;
		}
		unset($options['Statistics']);

		if(isset($options['StartTime'])) {
			if(!is_numeric($options['StartTime'])) $options['StartTime'] = strtotime($options['StartTime']);
			$options['StartTime'] = gmdate('c', $options['StartTime']);
		} else {
			$options['StartTime'] = gmdate('c', strtotime('-1 hour'));
		}

		if(isset($options['EndTime'])) {
			if(!is_numeric($options['EndTime'])) $options['EndTime'] = strtotime($options['EndTime']);
			$options['EndTime'] = gmdate('c', $options['EndTime']);
		} else {
			$options['EndTime'] = gmdate('c');
		}

		if(isset($options['Dimensions'])) {
			$x = 1;
			foreach($options['Dimensions'] as $dimKey=>$dimVal) {
				if(!in_array($dimKey, $this->_validDimensionsKeys, true)) continue;
				$options['Dimensions.member.' . $x . '.Name'] = $dimKey;
				$options['Dimensions.member.' . $x . '.Value'] = $dimVal;
				$x++;
			}

			unset($options['Dimensions']);
		}

		$params = array_merge($params, $options);

		$response = $this->sendRequest($params);
		$response->setNamespace($this->_xmlNamespace);

		$xpath = $response->getXPath();
		$nodes = $xpath->query('//ec2:GetMetricStatisticsResult/ec2:Datapoints/ec2:member');

		$return = array();
		$return['label'] = $xpath->evaluate('string(//ec2:GetMetricStatisticsResult/ec2:Label/text())');
		foreach ( $nodes as $node ) {
			$item = array();

			$item['Timestamp'] = $xpath->evaluate('string(ec2:Timestamp/text())', $node);
			$item['Unit'] = $xpath->evaluate('string(ec2:Unit/text())', $node);
			$item['Samples'] = $xpath->evaluate('string(ec2:Samples/text())', $node);
			foreach($_usedStatistics as $us) {
				$item[$us] = $xpath->evaluate('string(ec2:' . $us . '/text())', $node);
			}

			$return['datapoints'][] = $item;
			unset($item, $node);
		}

		return $return;

	}

	/**
	 * Return the Metrics that are aviable for your current monitored instances
	 *
	 * @param string $nextToken     The NextToken parameter is an optional parameter
	 *                                 that allows you to retrieve the next set of results
	 *                                 for your ListMetrics query.
	 * @return array
	 */
	public function listMetrics($nextToken = null)
	{
		$params = array();
		$params['Action'] = 'ListMetrics';
		if (!empty($nextToken)) {
			$params['NextToken'] = $nextToken;
		}

		$response = $this->sendRequest($params);
		$response->setNamespace($this->_xmlNamespace);

		$xpath = $response->getXPath();
		$nodes = $xpath->query('//ec2:ListMetricsResult/ec2:Metrics/ec2:member');

		$return = array();
		foreach ( $nodes as $node ) {
			$item = array();

			$item['MeasureName'] = $xpath->evaluate('string(ec2:MeasureName/text())', $node);
			$item['Namespace'] = $xpath->evaluate('string(ec2:Namespace/text())', $node);
			$item['Deminsions']['name'] = $xpath->evaluate('string(ec2:Dimensions/ec2:member/ec2:Name/text())', $node);
			$item['Deminsions']['value'] = $xpath->evaluate('string(ec2:Dimensions/ec2:member/ec2:Value/text())', $node);

			if (empty($item['Deminsions']['name'])) {
				$item['Deminsions'] = array();
			}

			$return[] = $item;
			unset($item, $node);
		}

		return $return;
	}
}
